Column thermostats are responsible for maintaining a constant temperature of the chromatographic column. Some column thermostats perform various tasks that require both cooling and heating.
ELUENT HEATERS generate a constant temperature for the solvent prior to entering the column.
COLUMN THERMOSTATS are available with different dimensions to enabling them to handle anywhere from one column to many columns, and from analytical to preparative columns.
To enable reproducible chromatography from run to run, it is mandatory that the column and solvent within the column are kept at a constant temperature. The column temperature must be stable not only for reproducible separations but for constant retention times. Increased column temperature causes a decreased solvent viscosity and therefore a lower backpressure. This enables your HPLC systems to run at higher flow rates resulting in faster analysis times.
ELUENT HEATING devices monitor and control the temperature of the eluents. It is important to have full control and overview of temperature settings and the actual temperature of the eluent.
WHY ARE BOTH COLUMN THERMOSTATS AND ELUENT HEATERS CRITICAL TO ACHIEVE REPRODUCIBLE HPLC RUNS?
It is extremely important that the column temperature is not only constant from run to run but that it remains consistent throughout the column. Separation temperature (column temperature) is instrumental in High Performance Liquid Chromatography (HPLC) since it can affect retention time, selectivity, and peak shape.
It is critical that the mobile phase (solvent) remains at the same temperature when entering the column, throughout the column and then as it exits the column. An accurate heating temperature must remain consistent from the solvent entering the column body, to the column body itself, and be precisely retained throughout the separation. Heating the mobile phase (solvent) without heating the column creates a radial temperature gradient whereby the center of the column is at the highest temperature and the temperatures gets cooler as it approaches the inside of the column wall. Conversely, heating just the column body creates an opposite radial gradient with the hottest temperature being on the inside of the column wall and the mobile phase is the coolest. If only the mobile phase is heated a longitudinal gradient is formed, with the hottest part being at the entrance to the column and diffusion throughout the column makes the outlet cooler.
WHAT IS RETENTION TIME?
Retention Time (RT) in High Pressure Liquid Chromatography (HPLC) is the time between sample injection to sample detection, most often with a UV detector.
WHY IS COLUMN TEMPERATURE SO IMPORTANT?
Proper column temperature control is essential for separations with marginal resolution. If the temperature of the column remains constant, retention times remain constant. Consistent retention times enable the chromatography data system to identify and properly quantify any components of interest.
BENEFITS OF COLUMN THERMOSTATS:
- Column thermostats increase temperature above the highest potential ambient temperature. The benefit of this technique is that it assures that the chromatographic run is performed under the same temperature every time. Ambient temperatures deviate from day to day and at different parts of the day, leading to inconsistent retention times causing inaccurate results.
- A significant increase in temperature reduces the viscosity thereby decreasing the back pressure in the column and allowing faster flow rates and decreased run time.
- A less common technique is to perform an isocratic separation using a temperature gradient to separate the compounds.
WHAT IS COLUMN TEMPERATURE?
COLUMN TEMPERATURE is a critical parameter in separations and affects the mobile phase viscosity and the analyte transfer between the mobile and stationary phase.
HOW DOES TEMPERATURE AFFECT ELUTION?
As temperature increases, retention time decreases. At higher temperatures, as retention time decreases, faster elution is possible. At lower temperatures, retention time often increases, especially in reversed phase separations. So, what is ELUTION? ELUTION is the chromatographic process of extracting one material from another by washing it with a solvent.
DOES TEMPERATURE AFFECT SEPARATIONS IN CHROMATOGRAPHY?
Temperature can affect the separation of components in all types of chromatography. This is because as temperature rises, the heat transfers into the solvents which promotes faster and more consistent run times.
ICON Scientific offers a unique preparative combination eluent heater and column jacket. This allows control of the temperature of preparative High Pressure Liquid Chromatography (HPLC) columns. Contact block heaters and convection ovens are available in different sizes and from different manufacturers. The column ovens can be controlled by chromatographic software. Some heaters are available with keypad control. Mobile phase heaters are optional on all units. ICON also offers peltier column thermostats, which allow the ability to cool as well as heat.
ICON Scientific, Inc
